The present invention relates to an oxidizing composition for treatment of keratin fibers comprising a combination of;                (a) at least one anionic associative copolymer,        (b) at least one anionic non associative copolymer;        (c) at least one peroxide agent;        (d) at least one persulfate agent;        (e) at least on alkalizing agent; and        (f) a carrier medium suitable for hair treatment.        
Conventional hair treatments such as dyeing, bleaching, and permanent waving or relaxing/straightening of the keratinous fibers, particularly human hair always require an oxidizing composition.
Human hair, mainly constituted by a-keratins is a sturdy and insoluble structure. One of the explanations for the strength and rigidity conferred to the keratin fibers present in the hair is the presence of large amounts of di-sulfur bridges formed with sulfur-containing amino acid cystein.
The actual role of the oxidizing composition can be multiple depending on the type of treatment. In hair colouring the role of the oxidizing composition is to decolorize the melanin pigment, lightening the underlying colour of the hair. But most important is its role to couple together the dye precursors to form the colored chromophores in the hair. For example, its major role in hair dyeing is to oxidize the dye precursors, which then being “activated” allows the cascade of reactions terminating with the formation of the hair dye. When used in hair bleaching, the oxidizing composition also has the role of gradually destroying the two natural pigments (eumelanins (brownish black) and pheomelanins (reddish orange)) embedded throughout the cortex. The characteristic natural gradation of the colour of human hair is the result of the combination of the ratio and concentration of these types of pigments. For example, while dark hair shows a higher concentration of the eumelanins, red hair shows a predominance of the pheomelanins. Light blond hair has reduced amounts of both. Experience has also shown that when aimed to be used to destroy the natural pigment of the hair, the oxidizing composition also destroys both eumelanin and pheomelanin, but at a different rate. Indeed, it has been found that the eumelanins are easier to break down than the pheomelanins. Because of these two different rates of destruction, dark hair when bleached leads to an undesirable warm reddish orange or “brassy” tone due to the enhancement of the red pigments. Finally, when used in hair bleaching the oxidizing composition also has to bleach previously deposited synthetic colour already present in the hair.
When typically used as a dye precursor activator in a hair dyeing system, the oxidizing composition mainly contains a peroxide agent in a concentration ranging from 0.6% to 10% on head by weight relative.
On the other hand, when used as melanin and synthetic colour destructor, the oxidizing composition present in the final hair treatment mixture would be typically provided from a peroxide developer comprising a peroxide agent in a concentration ranging of from 1.5% to 12.0%, by weight relative to the peroxide developer and a bleach powder comprising a persulfate agent at a concentration ranging from 10.0% to 40.0% of active oxygen (S2O82−) by weight relative to the bleach powder. Thus, the on head concentration of peroxide agent is typically 0.6% up to 10% for the peroxide agent and from 2.0% to 27% for the persulfate concentration by weight relative to the oxidizing composition (i.e. after mixing of the bleach powder and the peroxide developer at a 2:1 up to 1:4 ratio.
Being highly chemically reactive, the oxidizing composition, besides the role attributed to them, may also impact on the carrier medium of the hair treatment composition, undergoing some undesired side reactions. These reactions may have an impact on the different physical properties of the final hair treatment composition, such as the consistency and the homogeneity.
In order to be conveniently used by the consumer or stylist, the active agents, such as the oxidizing composition of the hair treatments are included in a carrier medium comprising various components, such as polymers, surfactants, stabilizers, chelants and aqueous carrier. These various additional components are important and necessary in order to obtain a composition providing the desired benefit to the consumer, with the actives principles but also enabling the consumer to use this composition conveniently without any harm.
Compounds known as “rheology modifiers” are crucial for any cosmetic composition, as they drive the necessary consistency for the composition, enabling the consumer to handle the composition and obtain the benefit. When exposed to an oxidizing environment, the rheology modifiers have an extra challenge of having to be chemically and physically stable to this highly reactive environment.
A rheology modifier enabling the maintenance of the physical stability of an oxidizing composition is described in U.S. Pat. No. 7,070,769 B2, wherein a composition comprising “at least two anionic associative polymers” is described. Also U.S. Pat. No. 6,547,833 B2 describes “a high aqueous-content developer formulation for use in a two-part composition for oxidative dyeing of hair, the developer formulation comprising at least about 70% by weight water, a peroxide oxidizer, and an acrylate/beheneth-25 methacrylate copolymer (Aculyn 28).
An object of the present invention is to provide an oxidizing composition suitable for the chemical treatment of keratinous material, such as, for example, dyeing, bleaching, relaxing, and permanent waving of keratinous fibers.
Among all the criteria required for a hair treatment composition, one very important criteria is the obtention of the desired consistency/rheology, or texture. This criteria is essential to allow the consumer an easy application of the hair treatment composition. In order to provide this easy application of the hair treatment, compounds giving a “thickening” benefit are used.
The main quality of a good rheology modifier is to be able to give the desired consistency when the final composition is prepared, during the treatment and until the end just before the consumer or stylist removes it from the hair. As well as having the desired consistency/rheology during the preparation of the final composition, a highly desirable rheology modifier would also maintain this consistency/rheology during the application of the composition onto the hair, until the end of the treatment process.
Usually, it has been found that the performance of the rheology modifier is highly correlated with the amount and type of oxidizing agent. As mentioned above, because of the highly chemical reactivity of the oxidizing agent, it is challenging to find effective rheology modifiers providing this benefit during the whole period of the hair treatment without a decrease of its performance due to interactions with the oxidizing agent present in the media; i.e. a great stability among all the other components of the composition. Thus until now, the only means to overcome this problem of maintaining the same consistency/rheology was to continuously and vigorously stir the oxidizing composition during application. This is inconvenient for the stylist and the consumer and results in an increase in the time required to apply the product to the hair.
Whilst not being bound by theory, the rational explanation for the alteration of the rheology and consistency profile during use is related to the observed phenomenon of “puffing up” or “foaming” or “swelling” behaviour of a typical oxidizing composition after mixing of the components. This is believed to be related to the reactions occurring during mixing which tend to provide in situ the formation of gas, such as O2 or CO2, which may be responsible for the swelling of the total composition. The bubbles of gas trapped in the composition may be released by applying a vigorous agitation to the composition.
This swelling behaviour of the final composition is a drawback, because it impacts the consistency of the final composition. Practically, having less compact and less dense properties, the composition would exhibit some difficulties for the consumer or stylist when applying the composition on the hair. Therefore some of the oxidizing composition when applied on consumer hair would have the tendency to drip or to fall off the hair, leading to a very difficult application of the hair-product. Much more critical are the swelling behaviours on hair after the application and during the development time because the swelling behaviour leads to expanded (bloated) foil packs or unlikely colouring effects on untreated hair when using free hand techniques.
Indeed conventional rheology modifiers, especially those involved in oxidizing compositions, tend to give a swelling side-effect when the components of said oxidizing composition comprise a persulfate agent, a peroxide agent and alkalizing agents. Depending on the amount of the alkali persulfate agent, the peroxide agent and the alkalizing agents present in the oxidizing composition used in the hair treatment, this results in swelling of the oxidizing composition. This foaming phenomenon is particularly excessive in the case of highly oxidative environments, such as bleaching compositions.
Particularly, in the field of hair treatment which uses oxidizing compositions (i.e. bleaching, dyeing, permanent waving or relaxing/straightening of the keratinous fibers, particularly human hair) there remains the need to have an effective rheology modifier, which is stable, and inert towards the active principles as well as the other components of the oxidizing composition. As well as stability as an essential characteristic for an acceptable rheology modifier, it is also desirable to identify a rheology modifier, which prevents the foaming behaviour observed for oxidizing compositions and overcomes the swelling behaviour.
In the present invention an oxidizing composition is described, which as well as providing a highly desirable property of maintaining the rheology of the composition during the hair treatment, also provides an effective decrease of the swelling behaviour of the oxidizing composition. Thus, the oxidizing composition of the present invention facilitates easy application of the composition to the hair and a very good adherence on the hair from the start application until the end of the hair treatment.
It has now been found that the specific combination of an anionic associative and an anionic non associative polymer used in an oxidative environment, as well as providing an excellent rheology performance, chemical and physical stability, also provides an effective decrease of the undesirable swelling behaviour observed in the oxidizing composition with other rheology modifiers. This specific combination has been found to provide excellent results, particularly with the so-called “Balayage technique”, where hair color is painted directly onto sections of the hair with no foils used to keep the color contained.